This invention is in the field of harvesting equipment and in particular devices for spreading straw and chaff expelled from combines.
It has long been recognized that straw and chaff expelled from the rear of combines should be evenly spread across the ground. The advent of minimum tillage and no-till seeding has increased the need for this even spread.
Prior art in the field includes U.S. Pat. No. 5,976,011 to Hartman, U.S. Pat. No. 5,797,793 to Matousek et al., U.S. Pat. No. 5,215,500 to Kirby, U.S. Pat. No. 5,120,275 to Zacharias, U.S. Pat. No. 5,021,030 to Halford, U.S. Pat. No. 4,917,652 to Glaubitz et al., U.S. Pat. No. 4,892,504 to Scott et al. and U.S. Pat. No. 4,617,942 to Garner, as well as Canadian Patent Number 1,179,567 to Clarke.
Different crops and conditions result in different spread patterns. For instance straw and chaff from wheat will generally have a different spread than that from canola or peas. The amount of moisture in the straw and chaff also affects the spread pattern. Generally the straw and chaff contains more moisture, or is xe2x80x9ctoughxe2x80x9d, in the morning and dries out as the day progresses, causing the spread pattern to vary through-out the day.
The variation in the spread pattern as moisture changes is caused in part by the fact that the location where the straw and chaff is expelled from the rear discharge of the combine can vary as moisture varies. The discharge area is a generally horizontal opening with a back wall and the spreading device located generally under the discharge area. When dry, the straw and chaff is thrown right to the back wall of the discharge area and falls down, however as moisture in the straw and chaff increases, it is not thrown as far and so lands nearer the front of the discharge area.
The change in spread pattern is particularly noticeable with a single rotor spreader such as that of U.S. Pat. No. 5,215,500 to Kirby. There, material falling onto the device in front of the center is directed largely out one side while material falling behind center is directed largely out the opposite side. In order to maintain an even spread, it is necessary to adjust the fore and aft position of the device as moisture varies. In Kirby as well, chaff moves only to the side and not the rear of the combine.
Present day combines cut an increasingly wide swath, up to 50 feet or more. As it is desirable to spread straw and chaff across the whole of the swath, increased spreading distance is required over that available in the prior art. The chaff, being very light, must be spread by an air blast, as any momentum imparted to a piece of chaff is quickly overcome by air resistance.
The prior art generally provides limited adjustment for changing the spread pattern for varying crops or conditions. Often it is only the rotational speed of the device which is adjustable. Adjustment of the amount of chaff directed to the rear of the combine is particularly limited in the prior art.
The prior art as well is often directed only at spreading chaff, requiring a separate mechanism for spreading straw. Devices which spread both straw and chaff, such as the apparatus of U.S. Pat. No. 4,892,504 to Scott et al., are often complex and costly.
It is the object of the present invention to provide a straw and chaff spreader for a combine that can maintain an even spread pattern in different crops and conditions, and yet is simple and economical to manufacture.
It is a further object of the invention to provide such a spreader that creates an increased air blast suitable for spreading chaff across the wide swaths cut by present combines.
It is a further object of the invention to provide such a spreader that includes improved adjustments for varying the amount of chaff delivered to the rear of the combine.
The invention provides, in one aspect, an apparatus for attachment to a rear end of a combine for spreading straw and chaff expelled therefrom, the combine having a left side and a right side relative to an operating travel direction, and a center-line parallel to the operating travel direction in substantially a center of a rear discharge of the combine. The apparatus comprises a frame adapted for attachment to the rear end of a combine generally under the rear discharge thereof such that straw and chaff expelled from the rear discharge falls onto the apparatus. A left substantially circular pan is rotatably mounted substantially horizontally above the frame on a left side of the frame, the left pan having an inside adjacent to the center-line, and an opposite outside and a drive extends through the frame to rotate the left pan in a clockwise direction when viewed from above. A right substantially circular pan is rotatably mounted substantially horizontally above the frame on a right side of the frame, the right pan having an inside adjacent to the center-line, and an opposite outside, the right pan mounted equidistant from the center-line as the left pan, a center of the left and right pans lying on a base-line substantially perpendicular to the operating travel direction. A drive extends through the frame to rotate the right pan in a counter-clockwise direction when viewed from above. A left wall extends substantially vertically from the frame, the left wall having a first end in proximity to the base-line in proximity to the outside of the left pan, the left vertical wall substantially following an outer edge of the left pan from the base-line towards the combine and around the inside of the left pan to a second end thereof located between 240 and 260 degrees from the first end, leaving a left opening of between 100 and 120 degrees between the first and second ends. A right wall extends substantially vertically from the frame, the right wall having a first end in proximity to the base-line in proximity to the outside of the right pan, the right vertical wall substantially following an outer edge of the right pan from the base-line towards the combine and around the inside of the right pan to a second end thereof located between 240 and 260 degrees from the first end, leaving a right opening of between 100 and 120 degrees between the first and second ends. A plurality of vertically oriented blades are attached to a top of each pan, each blade extending substantially from a center of one of the pans to the outer edge thereof. A lip extends from a front top edge of each wall substantially perpendicularly towards the center of the corresponding pan, the lip beginning at substantially the first end of the wall and continuing to at least the intersection of the base-line and the wall. A drive member extends substantially vertically from the center of each pan and rotating therewith and a straw spreader is attached to a top end of each drive member.
The double spreaders spread straw and chaff to each side essentially independently of the fore and aft location where it falls onto the apparatus. What falls on the left side is thrown to the left and rear, and what falls on the right side is thrown to the right and rear. Straw is spread simply by the apparatus as well as chaff, utilizing the same drive for both the upper straw spreader and the lower disc/blade chaff spreader.
The lip extending from the top of the vertical walls toward the pan centers acts to increase the air flow created by the blades and thus the distance the chaff is spread.
Adjustable deflectors may be added to allow the amount of chaff spread behind the combine to be varied.